One of the advantages of obtaining services on an Internet Protocol (IP) based infrastructure is the flexibility of being able to access services from anywhere with an Internet connection. Namely, customers are provided with flexible services and can obtain the same service regardless of whether the call originated from a home, a hotel, a dormitory, etc. When a customer requests for a service, the customer's telephone number and device are associated with the service. For example, a Voice over Internet Protocol (VoIP) customer may relocate a telephone adaptor to a new location and access services while away from home. However, some services are provided based on the physical location of the caller. For example, calls to obtain emergency service, e.g., 911 calls, are routed to the closest center equipped to provide the emergency service. For example, in North America, when a customer dials 911, the Public Switched Telephone Network (PSTN) determines the caller's telephone number, associates the call with a location (address), and provides the telephone number and location of the caller to the appropriate Public Safety Answering Point (PSAP).
When 911 calls originate in a packet network such as a VoIP network, the VoIP service provider is required by the Federal Communications Commission (FCC) to determine the telephone number and physical location of the caller so that the information is sent to the proper PSAP through the PSTN network. For example, the VoIP service provider may obtain the service address when a customer subscribes to a VoIP service. However, due to the flexible nature of the VoIP service, the customer may at a later time move the customer endpoint device (terminal adaptor) to another physical location and continue accessing VoIP services. Thus, the address obtained during the service subscription may no longer be usable for calls that rely on the physical location of the caller, e.g., E911 calls. The VoIP service then cannot be provided to the customer at the new address while meeting the FCC requirements for E911 calls. Namely, if the service provider is capable of determining that the customer has changed his/her location, then the service provider may deny or interrupt access to the VoIP service until the customer provides a new valid physical address.